1. Field
This invention relates to improvements in closures for containers, particularly for containers used for storing and dispensing sterile solutions and to a method for sealing the improved closures to a neck on the container.
2. Prior Art
For several years interest has been developing around flexible or semi-rigid plastic containers for storing and dispensing parenteral and irrigation solutions. Such containers have a number of advantages over glass containers in that they are less bulky, are not subject to shattering if dropped or bumped as are glass containers, and are more easily disposed. One of the main problems with plastic containers for such use was providing a closure system which would assure that entry sites would be maintained in a sterile condition prior to their connection with administration sets. One approach which appeared to provide such a closure system has been disclosed in U.S. Pat. No. 3,394,831. An inner closure having injection ports is sealed to the mouth of the neck on the container. The neck and inner closure are enclosed by an outer cap sealed at its base to an annular ledge on the neck whereby the outer cap maintains the sterility of the surface on the inner closure. Access to the inner closure is accomplished by pulling on a laterally projecting handle located between two grooves defining a tear strip on the side wall of the cap. Although this closure system accomplishes the purpose of maintaining sterility, there are several deficiencies associated with its design. The outer cap when removed often separates into two parts, i.e., the top and the strip portion, which can be a nuisance to the operator in disposing of these parts. The cap is difficult to remove because the pull must be made from the side of the cap. In addition the cap is difficult to mold and does not lend itself to being sealed to the neck by ultrasonic welding because of the obstruction by the handle.
U.S. Pat. Nos. 3,441,163 and 3,522,899 are representative of metal caps having a pull ring initiating a tear strip in the top surface. The score lines for the tear strip extend down the side, one extending to the bottom edge and the other only part way so that the cap is intended to be removed in one piece. These designs would be unacceptable for plastic caps; the tear strip would be severed completely from the cap since plastic tears more easily beyond an interrupted score line. The metal caps are also crimped around the neck of the container. This would be unacceptable for plastic caps since plastic tends to change shape under stress and thus a seal which assures sterility could not be achieved.
U.S. Pat. No. 3,545,638 also shows a metal cap of similar design except that the score line which extends only part way down the side terminates into a U-shape which is intended to prevent further tearing at this point and thus allows the entire cap to be removed. This cap is also compressed around the neck of the container and would not be acceptable if made of plastic.
U.S. Pat. No. 3,901,403 discloses a plastic closure having score lines in the top, one of which extends down the side or skirt portion part way to meet a circumferential score line. The entire top is first intended to be severed but remain joined to the skirt so that the skirt portion above the circumferential score line is also removed. The closure is made of material which is intended to elastically constrict around the neck of a bottle to provide a seal. This would be unacceptable for providing a seal assuring sterility. In addition, plastic closures having weakened zones for tearing in the top surface such as disclosed in this patent, are susceptible to having the tear strip sever from the top and leave the side intact.
Typical of a combination of inner and outer closure systems for parenteral solution containers in which the inner closure has two or more entry ports are those disclosed in U.S. Pat. Nos. 3,394,831, 3,905,368 and 3,921,630. In each instance the entry ports are parallel to each other. After the insertion of a spike of an administration set through one of two ports, the subsequent insertion of an additive solution or medicament through the adjacent port, particulary after the container has been suspended for delivery of the parenteral solution, is oftentimes awkward and difficult because the additive port can be obstructed by the administration spike and its associated drip chamber.
Spike entry ports with a rupturable membrane when made of plastic which is less resilient than elastomeric materials, sometimes do not retain a spike on an administration set when the solution container is in its inverted position. The ruptured membrane portion tends to push backwards on the spike to expel it. This problem can usually be corrected if the diameter of the port is made considerably smaller than the diameter of the spike. However, this is not a satisfactory solution since it becomes difficult to push the spike through the port.
With many plastic parenteral solution containers, in which an inner closure is sealed to the flange on the neck of the container by vibrational or ultrasonic welding techniques, particles of the plastic are often generated which then contaminate the solution in the container. This problem as well as the disadvantages enumerated above for inner and outer closures and spike ports have been overcome with containers of the present invention having improved inner and outer closures as herein disclosed.